Tips and Free Stuff

About Us

Buying Procedure






Old Website



GPRS Data Relay for DIY Vehicle Tracking 

 In August 2009 Zerksus is officially launching the new GPRS Data Relay service, GDR for short. This will allow the customer to either use Zerksus products or design and use their own products using GPRS devices over internet without developing any form of server.

This service is aimed at saving cost, limiting risk and getting up and running as quickly as possible.

How does it work?

First look at the alternatives.

  • If you are lucky you can communicate Peer-to-Peer between 2 SIM cards. That will only work on the same network and is not guaranteed to keep on working in the future. You are limited by your receiving modem's speed.

  • You may opt to go for an APN. Normally you have 3 options here: (1) modem to modem (fixed or dynamic IP), (2) modem to ISP or (3) modem to ADSL. The advantage is your communication is secure but your cost is much higher, and you are kind-of stuck with your configuration.

  • Internet APN but with your own leased line or fixed ADSL IP. You also need a server, basically for all the options so far, as well as your own software.

  • Modem to email. You need an STMP server somewhere on the net. The response is slow. You need special POP software to manage the emails. Lastly the email message might be dropped due to many factors. Without reason the server might see the many mails, from a single modem, as spam and lock your modem out completely.

  • SMS/MMS. Very costly but effective in certain cases.

What you actually want is to just log into some server to get your data. This is exactly what the Zerksus GDR does for you. The server sits in the middle of your application.


You have a small business with e.g. 5 vehicles and need to track them. You don't want to spend the huge costs to install a mainstream unit. So you design/obtain a tracking unit that will communicate via GPRS. This unit will now send data to a fixed IP address. So instead of getting such an IP address in the form of the alternatives above and having to develop your own software you sign up for the GDR. The unit now sends the data to the GDR server where it is queued for you. Whenever you require to download the data you connect via your client computer (from simple netbook, with 3G, to large system on ADSL). The data  is then downloaded and displayed, processed and stored on the client system. This system will now allow you to save costs by (1) installing your own unit, (2) not having to run an internet based service, (3) not requiring power backup and support and (4) not having to write software.


Additional features.

  • The server uses a standard API. This means that if you decide to design your own tracking unit or buy one of Zerksus's configurable tracking units (writing your own code) then you just need to fill in the required fields in the protocol and send. The protocol makes provision for 2 way data including SMS control (at extra cost).

  • Once the data is in the queue the server will allow you to access to latest data via a interactive web page. The web page also points free mapping web sites so you can view the location of the vehicle any where in the world where you have internet access.

  • You can have more than one client queue (at a minimal extra cost). This will allow you to create split control rooms or create a small queue (e.g. only last 5 minutes). The latter is very useful if you are the manager and just want to quickly log into the server to do a quick check. In this case you don't want to sit for hours waiting for the full queue to download.

  • Non-moving applications. One of the current applications is the Zerksus Gate Server. This system also uses a GSM modem to control residential complex gates. Via the GDR the administrator can configure the access and reports via the server using an interactive web page.

  • The server is hosted off-site in a 24/7 power protected complex with security. The server has a minimum of 100mbit/s internet link, soon to be upgraded to 1gbit/s. This means that there should be almost no data bottleneck.

Who is this service for?

  • Obviously Zerksus product clients using the tracking or Gate Server facilities.

  • Clients with custom GPRS applications who do not want to spend the big bucks on internet services, server costs, software development and support.

How easy will it be to implement?

  • You will have to register an account. During the process we will determine how you will pay for it. We do not provide credit. If you fall behind the service is suspended. Thus no credit application means faster registration. There is however an account registration fee, but no fee to add additional modem units.

  • In the case where you want to use a custom designed modem unit you will be provided with the IP address and port number, as well as the protocol. If required we can add you own custom protocol at an extra cost. If you use a Zerksus product then you only have to register the unit on the interactive web page.

  • You will be provided with the client IP and port numbers. If you do not want to use the Zerksus client software we can supply the interface protocol to you so you can develop your own client interface.

That is about it. The modem unit will now send its data to the server. The server will route it to the client queue. The client will download the queue to the client PC.

Airtime, data and queue costs.

You will have to look at 3 different airtime/data costs:

  • The server costs. We will include a monthly data cap on data traveling to and from the server. This is based on the number of modem units and not the client link. When this cap is exceeded additional data will be charged at roughly R0.10 per mb.

  • The modem costs. You will need airtime on the modem to send and receive data. In South Africa this starts at around R2.00 per mb and drops a lot if bundles are bought. There are many options to reduce the costs. The one contract option is to register an account with a network, cluster the SIM cards together and apply for a single data bundle to drive the lot.

  • Your internet costs from the client side. 

The modem costs are of particular interest. You can go for contract or pre-paid.  With pre-paid we do have a facility to top-up the SIM's air-time via the server. It will be the client's responsibility to always have funds available in the SIM account. Failure to do so will render the modem useless, requiring removal if you cannot top it up via another method.

Queue costs:

The queue cost is the main Zerksus expense you will have to pay. Depending on method of payment (upfront payment equals discount) the cost will vary. Also the more modems per client the lower the cost per modem. Currently the pricing structure sit between R15 and R20 per month depending on payment and number of units.

The data cap is based on the acceptable number of messages per month.  When the cap is exceeded the data will be charged additionally at R0.10 per mb. Just keep in mind that 1mb will allow for roughly 4000 messages (at large packet sizes of 150 bytes). If you send a packet every minute the modem will send 1440 packets per day and roughly 43200 per month. This will require about 12mb/month. Remember that you can decide how much data you want to send.

Optimal bandwidth usage:

It does not help just sending a few bytes. If you only send 1 byte then the modem still adds (or requires) 20 bytes for the IP header, 20 bytes for TCP (excluding routing data), possible re-transmits and other overheads. So the idea is to send large packets with several location samples compressed in the the single packet. The actual data sent must be larger than the GPRS overheads. In the case where you want focus on a vehicle you can send it a command to retransmit every few seconds (for live viewing) but that will eat up your bandwidth if left unattended. If you can wait a minute you will receive the same data, just more efficiently packed.

Checking our process.

You can check out the progress and launch date on the web site itself:  http://www.trackserve.co.za

Also be on the lookout for the client mapping software project providing you with cheap rent-able mapping data.




Home   Products   Services    Re-Package.com   News   Tips and Free Stuff    About Us   Buying procedure  Exchange rates        Last updated: 2009/07/30   

 2006- 2009 Zerksus Engineering CC.  Fax: +27 86 684 3042.    info@zerksus.com    Privacy Policy    Terms and Conditions                  Credit cards  accepted via www.setcom.com